Telephone-exchange system.



F. W! UUNBAR.

TELEPHONE EXCHANGE SYSTEM.

APPLILAHON mu) MAN 3, 1905.

131mm! .Ennv 38, my;

Inventor:

Fr'a ru'is Wlllunba r Wis? "(is was:

F. W. DUNBAR.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED MAR. 3, I905.

Patentvd J mm 1b, 1918.

5 SHEETS SHEET 3.

In m'n far.-

Witnesses: 41vj% oeooooooon 1' 'rar )1 c is W. Du 72 ba r F. W. DUNBAR. TELEPHONE EXCHANGE SYSTEM.

APPUCATiON HLED MAR 3.?135. 1,270,127.

ifiimlhwl Junv 18, 1918.

3 SHLES SHkEf 4- 3 Inventor-.- F 'dncz's W Dunbar filial;

UNITED STATES PATENT OFFICE.

FRANCIS W. DUNBAR, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESN E ASSIGNMENTS, TO KELLOGG SWITCHBOARD &, SUPPLY GOMI'ANY, A CORPORATION OF ILLINOIS.

TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

Patented June 18, 1918.

To all whom it may concern:

Be it known that I, FRANCIS W. Dunnan, citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Telephone-Exchange Systems, of which the following is a full, clear, concise, and exact description, reference being had to the accompanyingdrawings, forming a part of this specification.

My invention relates to telephone exchange systems, and is adapted to those classes of telephone exchange systems in which cord circuits are employed for uniting subscribers lines for conversation. The invention has for its object the prmision ot' a system wherein the calls are automatically distributed among the operators as the said. operators are free to manipulate the cord clrcuits. This distribution of the calls is preferably autonnitically eti'ected in the order in which the operators a re tree to take up the. Work of eti ecting connections; that is,a new call appears at the board or position of the first free operator. Thus, the first operator in a series of operators is fully supplied with work before the next operator is called upon to make connections, this next operator is fully supplied with work before the next. operator is called up n to make connections, etc, the operators as they become free being in position to receive nrw work, the. operators who become tree prcferably receiving the new work serially in their order. The signals operated by the calling lines are distributed among the on erators positions or sections. and aliiparatus is employed whereby signals amiearing at the ditl'erent operators positions or sections are dependent upon the number of cord circuits actually in use at said positions. Taking. for example, three adjacent operators positions in an exchange, the first operator is capable o1 handling, say, eight cord circuits, the second operator is capable of han dling seven cord circuits and the third on erator is capable of handling six cord circuits. As long as the. first operator has any of her eight cord circuits to use. incoming; calls are initiated at her position. If her eight cord circuits are in use and all of the cord circuits at the next opcratofs position are not in use, l'urthcr calls are then initiated at the second operatofs position. lt' this second operator has all of her cords in service, the cords of the first opera-tor then, of course, being in service, further calls are initiated at the third operators position, and so on. There is, as hitherto stated, in the system, apparatus whereby calling signals are not effected at those operators positions where the cord circuits are in service, but which are initiated at those positions where there are cords not in service, the inventi n being preferably so practised that the first operator in the series that is tree to make. connection. i th one al Whose position a call is initiated. In accordion-o with this preferred cmlvodinurnt ot' the invention. this call may be receired y operator No. l, opcrator No, l or an operator in the, series that is free and the first in order of the tree operators. 1 do not wish to be limited, however. in all enilu'idiments of my invention to the order of sequence in which the Free operators are selected to effect connection be, tween calling, and called lines. The great advantage of my present invention will be apparent: to thos skilled in the art, for by means of the invention the work of the operators is graded to their ca 'iacity and the calls are automatically distributed among the cu erators not according to the )hysical positions of illu board sections, lint according to the busy or tree condition of the operators, an operator being "frec who has not in use at her position all of the ord circults that have been assigned to her.

In the preferred embodiment of my invention. the cord circuits are associated with the line signals, there being preferably one such signal for each cord circuit and the answering ends of the cord circuits are preferably autoimzticaltr connected with calling lines, the connecting plugs being the only plugs that the operators preferably have to manipulate, though I do not wish to be limiiorl in all cmbm'limcnts of my invention to this precise way of practising the same.

The apparatus that controls the appearance of line signals at the operators positions, is preferably regulated by the cord or link circuits themselves, it preferably requirin the cooperation of all the link circuits assigned to a given operator to prevent the appearance of a calling signal at the said operators position, whereby if any of said link circuits thus assigned are not in use, a signal may be received that will cause this operator to use said circuit in effecting conneetion between lines. There is preferably one signal for each cord or link circuit at each operator-s position, but I do not wish to be limited to this characteristic. Where the answering end of a link or cord circuit is automatically connected with the calling line, I. prelere ly employ apparatus inter; posed between suhscribers lines and the cord circuits of all the operators, which apparatus first assmiatcs a calling line with the apparatus of an operator that is free to make con nections, and thereafter automatically to connect the answering end of an idle link or cord circuit belong ng to said OIJElltlXJl with said line. Thus, the first function of this interposed apparatus is to ellect association between it calling line and the apparatus of a free operator, after which the said appze rates is free to ellect connect on lielwn-cu one culling line and one of the link or cord circuits that free to be used. The ftppfllftllln for thus c-li'ecting association lee'n'msn cu Elfin: lines end. linl circuits, is prewutecl. from becoming ussocialed with a calling s gnal at an occupied operatofs position, l) reason of the instruun-nlalit jointly governed by the link circuits assigned to that operuior, which is so operated when all of the assigned link circuits are in service, that the appurutul for efiectlng the ass ulotion of calling lines w ith link or cord circuits, is forced to pr...s the apparatus of an occupied operator-s position and to seek connection with the n 'iparatits of a free (or partially occupied) operetors position.

Thus, viewing my system generolly, there are located at the venous operators posh tions calling signals in es.-.ciation with apparatus wherein sixid signals may only be operated at a free operator-s osition, the cords at the dili'erent sections of the hoard determining the operubility or" these signals.

I will explain my invention more fully reference to the nccompnnylng drawing, in which- Figure 1 illustrates the adaptability of the invention to one well known type of multiple so itch-board, the invention, however, not he lug limited to multiple switchboard prac ti e.

Fig. 2 illustrates the application of the in--- veution td another well known type of tool tiple switchboard.

Fig. illustrates one oil several modifiestions of the invention.

Figs. luiul 5 show other enlhmliuu-nts.

Lille parts are iiulicnle l by similar characters of reference throughout the rlltlcreut figures.

Each suhscriheids station, A. B, is provided with. customary common buttery sub scribers apparatus, a switch-hook at each station serving operatively metallic-ally to unite the sides of the line when the receiver is removed. I do not deem a detailed description of the subscribers apparatus to be essential, as the illustration 1s sufficient to make the same understood by those skilled in the art. Although I have illustrated one arrangement of suhscribers station apparatus, it will be obvious to those skilled in the nrt that other arrangements may be employed at the sub-stations, and I do not wish to be limited to the arrangement and apph rates shown, nor do I wish to be limited in all embodiments of the invention to its up pliceiion to a common battery system. The subscribers lines are metallic lines (though the invention need not be limited to metallic circuits), said lines extending in two l i'Hl'ltJllES to the exchange, where they ter minute in normal contacts l--2 normally en- ;mged by the urmutures 1'-2 of a cutoff role 3. The contacts l---2 are preferably ii. We form of spring arms that are adapted it,- rue-am contacts l -l" when the arnia in suid relay are attracted, such con )il lieiug broken when said armatures if err released. The contacts 1 l consi itn-ic the terminals of the office end of the line, which supplied with the line-jeck l.

."lhe system illustrated being a multiple awitch-hoard system, there are also provided upon other sections of the board than where jock l is located, other jacks 4: in similar connection with the contacts IL -1 That which in a. multiple switch-board would correspond to an answering-jack and in any other switch-hoard would correspond to a line-jack, is found in the terminals 5-6 which are normally connected with a sub crihers line through the agency of the nor innl contacts of the armature switches 7--8' of the relay The terminals l' -6 and associate parts are normally in the position indium-d cf. the right hand of the figure, in rendine to he connected with an idle link circuit. The contacts or brushes 5--6 ride over contact buttons l -8, which contact butbeing connected with a link circuit ton l selector switch element, has a rotating arm 9 connected thereto, there being one such arm 9 for each. button T, while. the contact buttons 8 are similarly connected with arms similar to the arms 10. Certain local. control to he hereinafter specified, is obtained in; the liruso or contact 11, the said elements or switch parts 5---6 moving together. ,The hrush l1 rides ov r contacts 12, each prefer :iiily connected with a rotating arm 13. All of the link circuits at an operators position urn in :msoeiution with the arms 9, l0 and 13, ilu l-ilking strands of said link circuits terminating in contncthuttons 14 -15 engaged y the arms 9-10, respectively, while local ill' lill conductors associated with said link (ll'tlillH are provided with contact buttons ll engaged by the arm 13. \Vhen the brushes 5, 6 and ll stop at one of contacts including :1 button 7, a button 8 and :1 hnmm 12,. they are then adapted to effect a signal at a free erators position, and in the preferred em odiment of the invention, are adapted automatically to be connected with a. link circuit corresponding to said signal,

there being desirably as many signals as there are link circuits.

In the system shown in Figs. 1.an d 3 the link circuit terminates at one end inthe contact buttons 9-l013 and at the other end in a connecting plug, the arms 9--10-13 automatically selecting the link circuit in a manner to be hereinafter specified, the signal corresponding to said link circuit thereupon being eflected, so that the operator thereupon uses the connecting plug 17 corresponding tO the signal.

In the system shown in Fig. 2 the link circuit terminates in an answering-jack 17 that may be assigned to operators and. dis tributed among them according to their capacity, signals being associated with thrse answering-jacks whose operativeness is governed by the operators connecting appara tus, so that the capacity of the operator at a given position will not be over-taxed. In connection with the system shown in Fig. 2 an ordinary form of cord circuit may be employed, including an answering-plug 18 for insertion within the answering-jack 17, the connecting plug 17 serving to be connected with the called subscriber.

Each line of a group of subscribers lines has many buttons 7, as many buttons 8 and as many buttons 12, as there are operators assigned or corres onding to such group. Itach subscriber ias thus assigned to him many groups of switches 910l3 (with their associate contact buttons) as there are operators, all of the switcl1arms 9-l0*-13 corresponding to a given subscriber, being desirably mounted upon a shaitlS of a link circuit motor 19 that is brought into operation under condi tions hereinafter to be set forth, when the subscribers switches 5-6--11 have become connected with the arms 9-10-13 of a free operator. Each subscribers line thus has a motor 19 that serves to operate the switches 9--10-13 corresponding to all of the operators, it being only such switches, however, that are connected with the switches 5-6 11 that )erform any function as a consequence of their operation. The switches tl--10---13 correspond to another subscriber and extend to contact buttons simi lar to contact buttons 7 8-12 cooperating with another subscribers switch including parts similar to parts 56--1l. All ofthcse arms 9'-10--l3 are adapted for,simultaneous operation by a link circuit niotor corresponding to the subscriber to whom the elements 91013 belong. By apparatus to be specified, the switch elements il--11 are brought into connection with the arms 9-10-13 that correspond to an operator who is free to take work, the said apparatus enabling the said switch elements 56-11 to pass by any arms 91013 that are associated with the apparatus of an occupied operator. In order that the parts 5--6--1l may be arrested in their travel (their travel having been commenced by apparatus to be specified), the cord circuits or link circuits jointly control and effect a circuit condition that will cause the motor mechanism operating the parts 5-61l to cease such operation when all of the link circuits that an operator is given to use arc not in service, thcsaid link circuits effecting another circuit condition when they are in use up to the capacity of the operator.

Without at the present time describing the apparatus by which the result presently to be stated is accomplished, I prefer to cause the link circuits belonging to each op orator and the apparatus for the purpose governed thereby, to place grounds upon the contact buttons 20 when all of said link circuits are in service and to effect the removal of said grounds when all of said link circuits are not in service. The contacts 20 cooperate with a switch element or contact; 21 that is mechanically coupled with the contacts 5611 to move therewith. When a ground is placed upon a contact 20, a circuit including said contact and the element 21 is established, that permits a continuation of the movements of the parts 5-6-11, said movement continuing until the element 21 engages a contact button 20 from which the ground has been removed. For this reason there is provided in association with each group of buttons 20 a grounded button :20 with which theelement 21 is normally engaged, sotliut the parts5 6-11 may be moved at once upon the initiation of a call. The wiping portion of the element 21 is broad enough to engage one button before leaving the preceding, for an ob vious reason. There is such a set of buttons 20 and a button 20' for each subscriber, each button of each set being associated with apparatus at one operators position, there thus being as many buttons in each set as there are operators positions or as there are sections of board. The buttons of tho different sets (corresponding to the dinerent lines) that are associated with the apparatus at one operators position, are multipled together, as indicated in the lower left-hand and lower right-hund corner of the dra wing, so that any switch clement corresponding to element 521 riding over a set of buttons corresponding to the buttons 20, by coming into contact with the first button from which the ground has been removed, will cause the operation of the parts similar to parts Bah--11. to cease.

I will later explain how the parts 9-10- 13 will stop when the engage buttons 14--1516 that correspond to an idle link circuit, and will also later describe the calling signal that is then operatedv 1 will now describe the apparatus by which the operation of the elen'icntu 5, 6, 1.1 and 21 is cmitrolled.

A calling subscriber, as subscriber A, by removing his receiver from its switch-hook, establishes a circuit at the exchange which may be traced from the grounded armature .1, over the subscribers line, to the contacts 2--2', the line-relay 22, to the grounded battery 23, whereby the arnmture-switches shown in association with said linewclay' are operated. ()ne of said armaturoewitches 24 thereupon establishes u circuit through a Winding 25 of a corresponding suhscriher s motor, which circuit may be traced from the ground at '20, the switch 21, the coullmlm' 2T connor 'ng said Switch with the front contact of switch :Z-l, the lazy arm .45. bot-Ween the bifurcations of which 1; projection of the armature 29 located, the winding 2 to the battery :3, The energizatiou of tliie' magnet. 25 is in n'iittcntly effected by reason of the sopur; relation. of the lazy :irin and its contact, so that the urn re 39 its: intermittently operated to engag the teeth 30 nu: hanically united with the Switch parts d lll] Thus, the first step s the movement of the part :31 from the grounded contact button 230' into engagement with the next button. Now, if the operator with Whose amiaratns the said. next button 'esioiiiated not free there will also be a grouin l upon and next but ton thereby still mointa'i'ining the c rcuit through the inagi'let 3:3. if the next Lillil'it' tor is fully occiuiied, the button 90 worn.- sponding to her position or board se tion also grounded and the movement of the parts o t-ll continued, this operation be ing carried on until the brush element 21 comes into contact with e b'lltl'fifl 20 that corresponds with a free o ierator, whereupon circuit throng] the magnet 25 cltectively opened, so that the parts 5i---6--11 --2l can not. be further moved thereby In the in.- stance illustrated at the left of Fig. l the Very first button i'U encountered by the switch part ill ie eup'poseil to be ilShUk'flilltlll with an operator who is not fully occupied. but who is free to put up more coinicctions,

' so that the (ircuit through the magnet 2.3

is opened to arrest the switch parts 5 1} -l l---.2l.. The ewiteh arms 9--10 l3 that are thus connected with the pelts 5--6--l1 as indicated, are those switch arms that are-associatml with the apparatus of the operator rorriniponding to the button )0 shown in connection with the clement 2t, whereupon the prime mover 19 is brought into service to more the said switch. parts 9---10---13 to connect the same with the answeringterminal buttons l4:-1516that may be connected or aseociatedwith the link circuit of the selected operatorithat may be used in, effecting connection between the calling and called subscribers, as'I prefer an automatic connection between the answering end of the link circuit and the calling subscriber, though that feature of my invention involvin the automatic selection of the place at which the calling signal is to appear is in itself a rcry important feature of the invention, particularly where the mechanism that is to govern this automatic selection of such location is jointly controlled by the link circuits. The motor that is employed for the operation of the parts 9--l0---i3 preferably includes a polarized operating magnet 31 whose armature oscillates alternately to engage teeth 32 in olfset peri jiheral rou'e, so that a sprin motor, which is; desirably coupled with tie shaft to, may step the said ehal't around, each :zmvei'nent of said shaft desirably bringing said parte 110 1 5 out of engagement with the contacting bottom into contact with the next buttons. The circuit including the electro-magnel. winding of the element 31 may be traced from the grounded generator 33 to be employed for operating said magnet, which generator ie preferably a source of alternating current, to the back contact of an i-matures itch 3 1, the armature-switch 35 and its front contact, to the armatureswitch 3t: and its front contact, Which,- is grounded. This circuit is broken at 34, however, during the time circuit is estabiislnail through the magnet 25 because the magnet 37 included in circuit with switch 2%, thereby removing the armature-switch 9w yrewnting the closure of the circuit thrrmgh the generator 33. This c-olmection 34 is provided because the magnet 38 is preferably employed to operate the switches 7-8 temporarily to disconnect the parts 5-6 from the callin subscribers line, circuit being establishe through said magnet 38 by the arn'iature-switch 39 engaging its front contact, the armature-switch 40 em gaging its front grounded contact, the magnet 35*, to the grounded battery 23. It mi ht be stated that the arnlature-switc es 24-35--39 are governed by the relay 22 and the arniiatlire-switches 3-14O are governed by the relay' 37. When the circuit through magnet 3'? is opened at 21, circuit through the elements 3133 is established.

in the embodiment of the invention. illustrated, while the motor 19 is in operation, in order that the ground at 36 may be maintained to continue the establishment of the circuit containing the generator 33, to which end the back or normal contact of armature-switch 40 is connected with the switch element 11, which determines the location of the ground supplemental to the ground at the battery 23 to establish this circuit of said magnet 38. By conditions hereinafter to be set forth, the contact buttons 12 connected with the apparatus at the different operators positions or board sections, have grounds placed upon the same through the intermediation of the switch elements 13, the contact buttons 16 engaging said switcharms 13 being grounded when the corresponding cord or link circuits are busy, and being free of this ground when such circuits are idle; So long, therefore, as the arm 13 is in engagement with the 'buttons 16 that are grounded, the circuit through the magnet 38 is maintained, and which may readily be traced as hitherto indicated. As soon, however, as the first idle link circuit or the button 16 corresponding thereto, becomes associated with the arm 13, the ground is removed from the element 11, causing the deenergization of the magnet 38, thereby removlng the armature 36 from its grounded contact. and opening the circuit containing the elements 31-33, so that the parts 91013 remain in the position they were brought to when the switch-arm 13 engaged the button 16 from which the ground had been removed because of the idle condition of the link circuit associated with the said button 16 thus engaged. All of the operators may be provided with the same number of link circuits, but the number of those circuits that may be brought into service may be limited by providing artificial means for placingggrounds upon the buttons 16 or otherwlse throwingthe link circuits out of operative relation with the operating mechanism of the exchange, there being indicated in the embodiment of the invention shown, manually operated switches 41 that may be moved into connection with grounded buttons when the link circuits associated with said switch-arms are thrown out of service. When the arms 9-10 are arrested, conductors 4243 of an idle link circuit belonging to a free operator, are connected with the arms 9 -10 and thereby with the buttons 7-8 and the switch arts 5 6 engaging said buttons, so that t e, calling line is connected with said link conductors 4243, for the armature-switches 7'8 are released because of the deenergization of the m net 38 accomplished as hitherto specifie il permitting the said armature-switches to engage their normal contacts and because efiect connection between the parts 11 and 21". The circuit through the cut-ofi' relay may be traced from the grounded terminal of said relay, to the armature-switch 8', the switch element 5, the button 7, the traveling-switch 9, the link conductor 42 (in this case the, sleeve strand of a cord circuit), the relay 48 (which becomes thereby energized), to the grounded battery 23. The subscribers apparatus now effects an operation of the calling signal 44, because the armature 45 of the supervisory relay 46 of the calling end of the cord is now unatt-racted, and because the relays 47-48 are energized, whereby circuit may be traced from the grounded terminal of the signal 44, preferably a small lamp, through the armature switch 49, the armature-switch 45, the armature-switch 50, to the rounded battery 23, this same circuit inclu ing a relay 51 com mon. to a plurality of circuits containing the signals 44 to operate a common signal 52. The circuit through the relay 47 may be traced from its grounded terminal, over the link conductor 43 (in this case the tip strand of a cord circuit), to a button 15, the engaging arm 10, a button 8, the engaging switch element 6, thence by way of the armatureswitch 7 and its contact, over the telephone line of the calling subscriber, the armatureswitch 8', the switch part 5 and engaging button 7, the switch-arm 9 and engaging button 14, the link conductor 42, to the battery 23 by way of the ma net 48. The supervising apparatus and t 1e balance of the operators apparatus associated with the connecting end of the cord circuit are well understood to those skilled in the art and need not have further description, oxce n that the armature 45, when attracted upon li'redn'sertion of a connecting plug within a called subscribers jack, serves to eli'aro the calling signal at 44. The operation in tin supervisory apparatus 53-54 and the signals supplemental to the magnet 55 will also be well understood from the illustration without requiring further description,

In order that the link circuit motors 19 may be prevented from stopping the arms 91013 to connect the same with a link circuit already in service, the buttons 16-16 coiiperating with the arms 1313' are multipled. In order that the arms 910 and 9'10' may be connected with any idle link circuit, the contact buttons 1414' are multipled, as are also the buttons 1515. The ground is placed upon and removed from the buttons 1616' through the agency of the switch element 11 and the button 12 engaging said element 11, which operation and attendant results will now be set forth.

The round that is to be placed upon and remove from the contact buttons 16-46 is 65 the cut-01f relay 3 has bec me e ergized .t indicated at the grounded erminal oi the 130 relav 56. When the switch-arm 1.3 (or 13, etc.) has encountered a button is (or 16', etc.,} having no cgnnection with a ground (the windings 25 and 37 having been do energized as hitherto stated), the nergize tion of the cut-off relay 3 is permitted due to the decnergization. oi the magnet 38 effected at the engaged groundless button 16. As a consequence of the deuergization of the line-relay occasioned because of the attraction of the armature 2'-in series with said magnet 22, the ground at 56 is thereupon at once placed in connection with the armatureswitches 39-4O and the switch element 11, so that allof the contacts 16-16, etc., united by the conductor 57 are grounded, so that no other switch-arm similar to 13 will pause at any contact connected with the conductor 57. The conductor 57 thus becoming connected with the ground at 56, has its circuit discontinued because of the energization of the magnet 47, whereby the magnet 56 remains in open circuit. The magnets 56 in the ex change are of resistance that is low relatively to the magnets 38 of the exchange, so that if a magnet 56 associated. with a busy cord is thrown into circuit with a magnet 38 of a calling line, said magnet 38 may remain operated without causing the operation of magnet 56.

If the calling subscriber restores his telephone before the operator has inserted the connecting plug 17, or if the operator has withdrawn the plug 17 after a completed conversation between connected subscribers, the calling subscriber then also having re stored his receiver, said conductor 57 will have its circuit extended by way of the armature 49, now released, the armature 45, also released,the armature 50, still attracted, to the grounded battery 23, magnet 56 will become energized to attract its armature and effect the engagement of the catch 58 in electrical connection with the armature of magnet 56 with the hook upon a grounded detent 59 preparatory to effecting the disengagement of said detent from. the rack 30, to permit the spring 60 to restore the elements r 5-6-1121-30 to their normal positions. The actual disengagement of the detent 59 is preferably offected by means of a spring 61 connected with the armature of magnet 56, to which end the circuit of said magnet should be opened, in order that its attraction may not oven come the force of said spring, the spring being upon one side of the armature pivot and the pole of the magnet upon the other. The spring 61' is permitted to operate because the magnet 38 is again included in circuit, by reason of the ground placed them upon at 59, causing the operat on ofthe switches 7 *8", and thereby the-d tion of the magnet 48, whose armature 50 whereupon the is released to open the circuit through the magnet 56, whereupon the spring 61 is free to effect withdrawal of the detent 59, so that the restoring spring 60 may mov, its asso ciate switch parts to their initial positions, a post 62 engaging the book 58 when such restoration is about completed, to effect dis" engagement between said catch and the said detent 59, placing this apparatus in po sition to take part in efl'ccting a new conuwtion. The circuit for the magnet 38 just mentioned may be traced from the ground at 59, the hook 58, the armature of mannet 56, the winding of magnet 38, to the grounded battery 23. After the parts 58--."i$ are separated, this circuit is opened. In UttSk the motor 25 should step the switch-contacts 5-6-11-21 over their entire range without having ell ected connection of a link circuit with the line-terminals fi -*6, I provide a means for effecting the restoration of said elements, to permit a re-operation thereof, To this end. 1. preferably provide a supplemental contact hutton 12' that is not con nected with any arm corresponding to arm 13,1111, is connected by way of a switch (33 with the battery 23, whereby said battery is connected with the switclyelement 11 when said element i in contact with the button 12. When the element 11 is thus connected with the battery 23, the circuit including said element contains the armatureswitch it) (because the element 21 is not in connection with the grounded contact, the magnet 37 thereby being in open circuit) and its normal contact, the armature-switch 39 and its back contact, and the magnet 56. The calling subscriber having manipulated his switch-hook to secure this result, thus m0- mentarily causing a deeuergization of the line'relay 22 to permit of the engagement of the armature-switch 39 with its normal. or back contact, the armature of magnet 56 is thereupon operated to engage the book 58 with the detent 59, whereupon the circuit including the magnet 56 is broken at 63 by the armature of said magnet, whereupon the spring 61 may withdraw the detent 59 to permit the spring 60 to restore the switch parts.

I have hitherto stated that before a cord or link circuit is to be automatically selected, a group of circuits belonging to a free operator is first to be selected, this in the embodiment of the invention being described hav ngbeen effect/ed through the agency of the buttons 20 and the conditions jointly im 'iosed upon each of the same y its nssnciale group of link or cord circuits, a group of occupied cords occasioning round upon its button 20, whereas a group 0% cords not altogether occupied ill cause its but ton $20 to be free of ground, with the results hitherto stated. The preferred instrumentality that I employ for controlling the application of a ground to each'button 20 by its group of link or cord circuits, is that illustrated, including the apparatus operatunder the laws of the Whcatstone bridge. The bridge of the Wheatstone circuit includes a polarized relay 64 whose po larized armature is grounded, such relay being common to a group of cord or link circuits and jointly controlled in its operation. thereby. In the operation of the VVheatstone arrangement more fully to be set forth, said armature is maintained in the position illustrated in Fig. 1 at the left when all of the serviceable link circuits of a given operator are not in use, so that the conductor 65 terminating at one end in a contact button 20 and at the other end in a contact for the said armature, is under such condition free of ground connection, but when all of the serviceable cords are in use, the said armature is swung to its alternative position into engagement with its contact, the terminal of the conductor 65, so that ground is placed upon the contact 20 corresponding to said group of link circuits, forcing the switch elements 5611-2l to continue their movement. as hitherto set forth. The direction of movement of the armature of relay 64 depends upon the direction of current through said relay from the battery 23, this battery 23 being connected between two adjacent sides G667 of the VVheatstone bridge containing the fixed resistances. The other two sides 68-439 of the Wheatstone bridge are grounded, and, as the battery 23 is grounded, the \Vheatstone bridge arrangement that I have described is completed, for there is included in the side 68 resistance that is automatically adjustable through the agency of the link circuits, such adjustment being efl'ected as said link circuits are put into and withdrawn from service. the other side 69 containing a resistance 70 that is to be adjusted manually according to the capacity of the operator using the cord circuits associated with the relay 64. The resistance of the side 68 is preferably composed of a number of sections 71, each cord circuit of a group having one such section. The relay 48 of each link circuit has an armature-switch 72 that engages a grounded contact when operated by said relay to include the corresponding resistance section 71 in ground connection. The resistances 71 are thus connected in circuit as their associate link circuits are busy and are excluded from circuit when said cir shits are restored to their normal or idle conditions; The resistance 70 is adjusted by hand to determine the time at which the current through the relay 64 shall be so directed as to effect an application of the relay armature to the terminal of conductor 65 associated therewith. Each operator may have ten link circuits, but the resistance 70 may be so adjusted that the moment six, for

example, of the resistance sections 71 are connected to ground, the armature of relay 64 will be connected with conductor 65, so that the selecting mechanism of the subscriber calling will pass the button 20 connected with conductor 65 thus grounded, until the element 21 of said selecting mechanism will engage a button 20 from which the ground has been removed. Thus, the operator having the relay 64 cannot attend ,to more than six connections at a time. If the capacity of the operator is greater than six connections, say eight, the resistance 70 is correspondingly adjusted to permit the inclusion of eight sections 71 abreast before the conductor 65 is grounded through the armature of the relay 61. As soon as the predetermined number of sections that may be included abreast is diminished, the current through the winding of relay (S4: is reversed to remove the relay armature from connection with the conductor 65. A relay 73 belonging to another group of link circuits, is illustrated, the armature thereof being shown applied to a conductor H (as the serviceable link circuits corresponding to said relay are occupied), said conductor be ing connected with a. button 20 of a group.

.The system shown in Fig. 2 employs link circuits terminating in answeringjacks 17, cord circuits, each including a connecting plug 17 and an answering plug 18, being also employed. 1

The subscribers line and exchange apparatus possess parts similar in function, arrangement and operation to parts that are correspondingly designated in Fig. 1. The link conductors 42-43 extend from the but tons 14-'15 to the sleeve and tip elements of the answering-jack 17' adapted for electrical connection respectively with the sleeve and tip of the answering plug 18 when said plug is inserted. The magnet or relay 47 is connected with the conductor 13, as in the system shown in Fig. i The calling signal manifested at 44 is efl'aced when the operator inserts the answering plu 18 because the circuit of said signal inclu es a switch 45 that is opened by said answeringplug when thus inserted.

The elements in association. with the link circuit illustrated in Fig. 2 that. are designated similarly to elements shown in association with the link circuit of Fig. 1 have similar functions. The cord circuit appa ratus illustrated in Fig. 2 is well understood tothose skilled in the art and need not be described.

The apparatus illustrated in the system shown in Fig. 3 is generally similar to that shown in Fig. 1, and parts possessing similar functions are similarly designated. In the system shown in Fig. 3 thecut-ofl' relay 3 depends for its circuit controlupon a con,

ductor 76 that is not a talking conductor as is the case of the conductor that is depended uFon for this control of the cut-oil relay 3 0 Fig. 1. This conductor 76 includes not onlythe cut-otf relay 3, but an arrmitureswitch 77 operatedby the magnet 38, switch brush 78 and one of'a set of connected buttons 79, there being one such set of connected buttons for each group of cord circuits. A switch-arm 8O operated by the motor 19, is on the same shaft with the switch-arms 910-13, said switclrarms 80 riding over buttons 81 having connections similar to that established by, a conductor 82 with the battery 23, whereby the cut-oil rel-av 3 is energized upon the connection of a calling line with an idle link circuit. Various parts of the system shown in Fig. 3 are given characters of reference. the parts having designations similar to parts in Fig. 1 having similar functions.

It is understood that there is one conductor to each group of link circuits assigned to an operator. I have shown only one link circuit 42--l3, though it is to be understood that there are as many such link circuits as there are buttons 14 including the button 14 connected with the conductor 42 and as there are buttons 15 including the button 15 connected with the conductor 43. The switch-arms 9-10 are adapted temporarily to constitute the traveling terminals of any calling line that has selected the same, which traveling terminals ride over the answering buttons of the link circuits. In the selective mechanism illustrated, the line that calls, first selects the switches 9--l0 that have the capacity of being connected with an idle link circuit; that is, it selects such switches 9-10 whose associate link circults are not all busy. In this way the selective mechanism may interchangeably select the terminals 9-40 as continuations of different calling telephone lines for the purpose of having the same temporarily not as the traveling line terminals of the calling line, such selective mechanism being dependent upon the electrical condition of the button 20 engaged by the element 21. If there are, for example five thousand lines and thirty o erators assigned to the same, there are t irty roups of traveling switches 9-10 0perated, y each motor and coupled with any associalte switches, as th switch 13, in the case ofiFig'. 3. There are, consequently, as man b ttons 20 as there are operators, w maybe said also of thebuttons 8, the buttons 7, the buttons 12, and the button '5' 9. There are as many motors 19 as there are devices containing the parts 5 6-11, etc. Inasmu" as in the embodiment of the in vention shown the parts 5-6 are preferably ossociated with the telephone line, there are thus, in the example stated, five thousand such motors 19 each adapted to operate thirty groups of switches 9---10--l3. To

make the illustration more clear, itmay be specifically stated that all of the link circuit conductors leading from the contact buttons l-l----l5, etc, associated with each set of arms 9------l0, etc, extend to one o iierators position, the link circuits extending from another set of such buttons extending to another operators position, and so on for each of the thirty in the example chosen. The lowermost set of buttons 14 etc, may, for ear-- ample, be connected with all of the link circuits extending to the first operators position, the group of buttons 14c-15, etc, next above the last group mentioned may extend to the second OPGISLCOISS position, and so on until all of the thirty operators have received their link circuits. While I employ a ri-ctilineal o'ierating switching appliance 5-- 6 --ll c' 1. ,.or each Slll')S(3I'lb5I, I do not wish to be limited to a selecting device hav ing this characteristic, nor do I wish to be limited to the rotating arms 9-10, etc, nor to the. precise motor mechanism and its control t'or effecting movement of said arms, nor to the Whcatstone arrangement controlled by the link circuits of each set for governing the appearance of calling signals at the operators position corresponding to said set.

In Fi 4. each subscribers station, A, B, is provi ed with customary common battery subscribers apparatus, a switch-hook at each station serving operatively metallically to unite the sides of the line when the re ceiver is removed. 1 do not deem adetailed description of the subscribers apparatus to be essential, as the illustration is sullicient to make the same. understood by those skilled in the art. Although I have illustrated one arrangement of subscribers station apparatus, it will be observed by those skilled in the art that other arrangements may be employed at the sub-stations, and I do not wish. to be imited to the arrangement and apps ratufs shown, nor do I wish to be limited to its application to a common battery s stem. The subscribers lines are met-a lic lines (though the invention need not be limited to metallic circuits), said lines ex tending in two branches to the exchange. In Fig. 4 these lines terminate in normal contacts 1-2 normally engaged by the armatures 1--2 of a cut-oil relay 3. The contacts 1-2 are preferably in the form of spring arms that are adapted to engage contacts 1 when the armatures of said relay are attracted, such connection being broken when said armatures 1.'2' are released. The contacts 1 -4" constitute the terminals of the office end of the line, which is supplied with the line-jack 4. The system illustrated being a. multiple switchboard system, to which my invention is not limited. however, iiicre are also provided upon other section of the board than where jack 4: is located rt ho 4 in similfl' connection with the contacts 11. When this connection. There are magnets 87- a subscriber initiates a call, a circuit is es- 87-87 etc, one for each of the contacts tablished, that may be traced from the 86-86- S6 ,etc., all of which are connected grounded battery 23, to the line-relay 22, with the operators conductor 65 and with 5 the now released armature 2', the contact 2, the buttons of the sets 86-8686 that are 70 over the line of the calling subscriber, the connected with said conductor.- Thus, contact 1, to the now released grounded arwhenever said conductor 65' is connected mature l. The armature-switch 83 is therewith a grounded battery 23, through the by moved against its contact, that is groundagency of the armature of the polarized reed, thereby establishing a circuit that may lay 64, all of said relays 87-87'87 are 76 be traced from the grounded contact 'of connected with said battery. When the switch 83, to the armature of magnet 56" element 85 or similar element riding over a (which, with its associate apparatus, is group of Contact buttons 86, or similar common to a group of lines, taps 84 extendgroup, enco ters a button of such group ing from the switches 83 of all the subscribthat is thus grounded, the grounded relay 80 are lines belonging to said group bein 56' connected with the element 85 is thrown shown in common connection with the sai into connection with said battery 23 a cirarmature of magnet 56') the contact norcuit at the same time being established mally engaged by said armature through through the corresponding magnet 87, 87' or the agency of the spring 61., the lazy arm 87 etc. The armatures ofamagnet 87, 87 or 85 28, the operating magnet 25, to the ground 87 having been attracted, circuit is ei'l lier ed battery 23. A terminal of the windin Wholly or partially completed through the 25 is in the form of a contact with whicE magnets 8888-88 corresfponding to the the lazy arm 28 is adapted to have separamagnet 87 and its group 0 subscribers or 25 ble engagement, the lazy arm being bifur- 89-89-89 corresponding to the magnet 90 cated to receive between its bifurcated ends 87' and its group of subscribers, or the magan extension of the armature 29. The arnets 90-90 90 "corresponding to the magmaturc 29' is thus intermittently operated net 87 and its group of subscribers, whereby (during the continuation of conditions hereapparatus that will be specified, is set into 30 inafter to be set forth) to engage the teeth operation to connect a link circuit with the 95 30' upon a bar to effect the movement of a terminals 5-6 of a calling line, but, before switch part 85 over a group of contact butdescribing this operation, I will state how the tons 86, there being one such element 85 and element 85 and the associate parts are reone such group of contacts 86 for each group stored to their initial Eositions in readiness of subscribers lines. Each horizontal row to be operated by anot or calling subscriber 1 of buttons 86-8686 is connected with a of the same group, to initiate a new connecconductor, such as associated with a tioin Particular description hereafter will group of link or cord circuits, and there are be given of the apparatus cooperating with as many such groups of cord circui'ts as the element and one line of the group 40 there are horizontal rows of such buttons. of subscribers to which the said element be- The electrical character of these buttons delongs, for from this description the operapends upon whether or not their associate tion of the exchange apparatus associated cord circuits are fully occupied. By appawith the other groups of subscribers lines ra'tus to be presently set forth, if a group will readily be understood.

5 of cord circuits in cooperation with any of Speaking now of the release and restorathe buttons 86-86-86 is not fully occution of the eleme nt 8-3 and its associate parts, pied, that button is grounded through :bat ground is imposed upon the conductor 91 tery 23; if said group is fully occupied, batthrough the ago'z'lcy of an armature or artery is removed from said button, with the matures connected therewith and belonging 50 results to be presently set forth. The link .to the ma nets 8888'-88 Prior to the circuits associated with the buttons 86- location 0 this ground upon this conductor 868G etc, may be distributed among the 91, the magnet 56' is energized to withoperators as desired. The lowermost condraw its armature and effect engagement tact buttons of the groups 868682 are between the hook 58 and the detent 59, and,

56 shown in circuit relation, from which. upon the connection of the conductor 91 illustration the circuit relations of the rewith the ground, the magnet 56 is shunted, maining contact buttons will readily be un-' whereupon. the spring 61 may move the derstood. Each conductor 65' is connected hook 58' and withdraw thetdetent 59 from with an armature of the polarized relay 64 the engaging tooth 30, whereupon th 60 and thereby with the grounded battery 23 spring 60 will restore the element 85 to its whenever sufficient sections of resistance 71 initial position. In case the element 85 have been cut out of circuit by the released should have traveled its full course without armatureswitches 72, properly to direct the having become operatively associated with current through the winding of said relay, a conductor 65 extending to a free 0 er- 65 to force a movement of its armature to effect ator, a supplemental button 85 is provi ed,

\vhirh ii: eonueeleii with ille initial; 2;} o n-ruli'vely navoviuimi with the link oil-units through the :igenuy nlihe switch Gigi. \Vhen oi one operator or :it one hoard. section in the element 85 engages the button 82), eirthe iiil i-iiiili lUli shown There are n54 mini euitthrough the magnet in rinsed and; such new, of hWliLfillGS 1):" 92 $2 11S 11 its armature in attracted to c-ingg nge the hook are gronpn ol' enlwerihers and the mritehen 7U 58 with the detent 5W, 'n'luirinrlier said ii one hlri are in ninltil will *YlUT-lmi armature engages the snvileh or to open the of eznxii f the oiln'r eels. Eneh set of circuit ihrongh the magnet lr lfi, pwrini ,ting rie ulie't hm n :noini' than nerves to operate the spring (-1 to withijiriuv [he (iliififfiil 59L iiie mime imieminientiy of enuh oi. the other so that the spring Kl inny roeztore the eleno, it uioior M being shown for the out of 75 inent 85 and its 2 ssoeinte partsto their iniswitches 92. it, Ming understood that the set trial positions. As was the (new with the ol' mi e'hen iii!" and 332 eneh have at eor-l or parts numbered 62 and in Figiifi niul iink (ch-run nmlor similar to 5H3 for opt-mt so with the parts 62 and 55 in the pieisent ing ihe Hume. this being the preferred form instance, the post 62 moves the hook 58" of motor for he purpose desired. Each 88 out of engag nient with the detent 5i) button of lhe mi 86 has it inngnei HT and as the spring 60' is completing the restore conductor vi associated therewith, each lion of the, eleinent 85. group of -iubz-ierihors, therefore, having as Having w operated the element: n it nmny Huh magnets 37 and roiuluet -r-= 91 select a il (llflillcifil iri aszsoeinteii with :i, ire: m e-r are notions S6; in other r. operntmunri having placed at ground upon. ihwe are grl'enim oi word. 'or iinli viz the conductor Si in ihe mourn hereinal'iw n ill). which said hnitons 86 eoil www- (0 he speiifieri, wherein rirruiis ilwoufli armature oi (nah inzigne pnrlinih wor the i'r tgnets $T---- 8T- m" am;- trthe ireuiis oi and coiipmatio; 1% independently of thee emen i a many nuie'nete --ll"3'-c" am: :i(5S(lihQ the Wnj; in whirl; i3

coin romi minors 93. one]; roi'zi riiljni'i ends of link oircintn seek the 1114144,! 51 ifl having :1 nuigni-n vfine?) u rl? "iii :in

lli lines, i'rnntwiiing its opernifility All of ii'm eerii In order that further Jenirintaon of the in? motors adapted independently to systeni now being eol'isiriered nney he more oral-a the switches 9'2--92-93* vii-long; ng Q5 readily nndergtood, i will first iightly refer to lfil: linlz circuit, have. unsigned thereio the link circuit nppnrni'ns. and some of to w eontroliin g magnets as elf-i i). the meehanisn'i wheroliiy connection is elieot- All of he (m-1i circuit motors iliiililflifiii ed between a link circuit and coiling lin re understood to he ni seeiaieii with Each line terminates in n pair of cont; iiul; rironih-i of u single group, there it? i. buttons 5-6 that are in ninltipie with the nanny 41m of said cord or line: line-jacks 44 anti each linl: rireniii moiern n there are cords that may he made m'inntes in traveling switch-arms nvniia le for serviw 'in each group, thoan-i 92". etc. Each anlilseril'ier line it pair i gun min] or link inrrnil's that an our-Valor is mtact. 5-6 in each C( iii or liulr own, of Lt iil' it to handle being opemtiveiy viie oeiniwi 1435 group of such link eirrniis. rin'ii": eontsie ii" in tlii vstem Space nines not pern'zit iilne one link eironit moire; Tllill. .l with imiion of another group of cord or iuilt lareontnets of iltfifltllfil link in-um. 1 ,i eireuit moiorit out it is to he ir 'er-iljiwri cord or link circuit has sent i w men that l'ilifll wmlucfer F- 'i and tinerawrre. eeen suhscribers line and switeln, sneh as 92, horizontal row of buttons 86 -8(5'-- :it5 i112, no riding over the contacts of all 3f the correhas: such a group of cord circuit motore 1on3 spending group of suhserihers lines, the {ii-EH (F t6 nppnratns, A free operator hmfirst division of each cord or link oirr-nit ing been selected, the cord or link i i.rvuit of having the contacts 5--G of the group of such operat r that is not in service. is new subscribers lines corresponding in the first to be seieeteih to which end only the link row of buttons @36, the next division having eirenit motor that eorrespmids to the group the contacts 5"---6' of the group of sni of snheerihers containing the calling Suhseribers lines corresponding to the second, ra riljaer s to be operated. The motors; that row of buttons 86" mini the next liViHiH]! inong lo each link or cord circuit are. there having the contnetS 5 of the group of form nude in partially eontroi the riremts 121) subscribers lines corresponding to the third. inruniing such magnets as SS fi rte, so

row of buttons 86, and so on, emh curd eirthat such magmas will only effect (he operunit being divided into as many divisions ntiun of motors associated with itile link suhsorihere lines. iii'l'illlt. To this and (tfl'll motor has upon.

as there aw groups 0..

in modem u "ilfilllli he Filililfli that :19- eneh ifs whnfi a notched wheel 9+ upon which. 125

ronilnctor (35 is nesoeinimi with :1 n orieiaior riiiei; the tooth of a nwitch 95. \Vlien. the or a group of link circuits and i ronmirteil link mite anso-oizitod with motors are not through the relays S7- --8T 8i' with the in use, lhoie'eth of the switches 95 are in buttons SFF'M-SG'JWQG in (he Slllllf' lioriiioniini the notrl ws of lhe wheels 94, whereby the row, eaoh horizoniul on of such buttons 55; ewiiehes Li? engage their normal contacts, .30

which, with the switches, are serially included in the conductors 96-96-96 and when said conductors 96--9(i'-96 are thus closed, circuits are completed including the same, when the armatures of the magnets 87--87'5'i are attracted, these armatures constituting terminals of said conductors, the circuit ultimately closed by said armatures containing the battery 23. The corn ductors 96--9b96 include the magnets 88 89 --9O'-- 88--89---- 90---88 89 90 in circuit, these magnets connected with said conductors 96--96--9G being connected in parallel. The magnet 88 governs the left hand motor 93 of the top cord circuitapparatoss, the magnet 89 governs the next motor to the right, and the magnet- 90 governs the next motor to the right, and so on. A subscriber of any group is thus enabled to be come associated with any operator, but each subscriber is limited to cooperation with those sections of the cord or link circuits of a selected operator that correspond to the subscribers group. The first section of each cord circuit thus corresponds to the group of lines associated with the buttons 86, the second section of each cord circuit corresponds to the group of lines associated with the buttons 86, and the third section of each cord circuit corresponds to the group of lines associated with the buttons 86. Thus, the first section of each link circuit effective in completing connection with a calling line associated with the group-of buttons 86, the second section of each cord circuit is effective in completing connection with a calling line associated with the grou of buttons 86, and the third section of eac 1 link circuit is effective in completing connection with a calling line associated with the group of buttons 86 It will be seen that each circuit (for example the circuit asso riated with the top row of elements 94) is capable of having the magnets 88- 89--9O associated therewith, the magnet 88 thus corresponding to the first section of this particular cord circuit, and, consequently, being associated with the group of lines associated with the buttons 86, the magnet 89 corrcsponding to the second section of this particular cord circuit, and, consequently, being associated with the groui of lines associated with the buttons 86, and the magnet 90 corresponding to the third section of this particular cord circuit, and, consequently, being, associated with the group of lines associated with the buttons 96 in the illustration. however, one of the elements 94 has been shifted because the as sociate link circuit is busy, so that no one of the magnets HS--89-.)O may be operated. The link circuit associated with the next lower row of elements 9% is also busy, as indicated at the central element 94 belonging to said link circuit, thereby pre- Ill. Li.

venting the operation of the ma ets 88' 89'--90'. The bottom row of e ements 94, however, are in a normal position, so that circuit may be closed throu b one of the magnets 88 89 --90 accor ing to which of the magnets 87-87'-87 is energized and according to the group containin the calling subscriber. 1f the call shoud be from the group of subscribers corresponding to the button 86, the magnet 87 would be energized and, consequently, the magnet 88, so that the lowermost motor 93 at the left will be operated, as this is the motor that corresponds to the magnet 88, the magnet 87, the group of contact buttons 86, and the group of lines associated with said buttons. It will be better for the understanding of the invention, however, to assume that connection has thus been effected between a calling line of the first group of subscribers lines (corresponding to the buttons 86) and that link circuit corresponding with the upper row of elements 94, to which end, prior to making such connection, it should be assumed that the left hand element 94 has its notch engaging the tooth of the switch 95, whereby the armature of magnet 87, operated, by the calling subscriber, is attracted, to establish a circuit that may be traced from the battery 23 by way of said armature of the magnet 87, to the magnet 88, thence by way of the conductor 96 thron h the switches 95, to the ground at the le t hand switch. The magnet 88 is thus energized to'establish the ground upon the conductor 91 that causes the short circuiting of the magnet 56, with the results hitherto specified, and to place a ground upon the lowermost armature of said magnet 88, this latter armature establishing a circuit which may be traced from the ground put thereupon, to the rotating switch 97 upon the same shaft of the switches 92, said armature of magnet 88 bein connected with a button 98, the switch 7 normally restin in contact with the button 98, which normal contact is efi'ected when the notcli of the associated element 94 engages the tooth upon the associate switch 95. Thus, it will be apparent that there are. as many groups of magnets 888888 89-8989 etc., as there are divisions of cord circuits and as there are groups of telephone lines, the first divisions of the cord or link circuits, the first group of magnets, such as 88, and the first group of telephone lines corresponding to buttons 86 being cooperatively related, while the second divisions of the cord or link circuits, the second group of magnets, such as 89, and the second group of telephone lines (those associated with buttons 86) are cooperatively related, and so on throughout the system. There are many magnets 88--88 etc., 89-39, etc, and 90- 90 etc., in each group of magnets as there are cord circuits, whereby each cord circuit has as many magnets as there are divisions of telephone lines, and whereby each section of each cord circuit has one of such magnets. The calling subscriber having thus selected a free operator and his section of a free cord or link circuit belonging to said operator, causes the motor 93 to start, whereby the traveling answering 1.0 ends or terminals 92 92 are caused to travel to seek the terminal contacts 5-6 of the calling subscribers line. It is well here to state that if there should happen to be several link or cord circuits idle at a se 15 lccted operators position, a motor 93 of each of said circuits will be set into operation, the arms 92 92 that first encounter a multipled pair of contacts 5-6, however, being the arms that are employed to cflect connection between the link circuit and the calling subscribers line, to which end the multipled buttons 5--6 of different sections are preferably circularly displaced, so that two cords will not be simultaneously com nected with the same line. Since, as soon as a line is selected, its line relay is deenergized responsive to the operation of cut-oi! relay 3 hereafter described, the armature 100 retracts and reconnects ground to so the multiple contact buttons 101 of the line so that the arms of any other started selectors engaging the contact buttons of a selected line will pass on and continue their travel in. a complete circle to normal, unless of course there be a second calling line in the group in which case the arms of one selector will select the buttons of such line. As hitherto stated, the subscribers of the first group corresponding lo buttons 86 have their terminals 5 6 in the first sections of the link circuits; the subscribers of the second group corresponding to buttons 86 have their terminals 5--6 in the second sections of the link circuits; and the sub scribers of the third group corresponding to buttons 86 have their terminals S 43 in the third sections of the link circuits. It will be seen that any operator when free may have her link or cord circuits operatively associated with a calling line in any group of telephone lines.

. I will now describe the mechanism where by the selected motor 93 is permitted to operate.

Said motor has a wheel upon the same shaft that carries the arms 92 -497, which wheel is provided with teeth 32 arranged in peripheral rows, an armature of a polarized relay 31 oscillating from side to side alternately engaging the teeth of said rows,

the tenth of one row being olfset with respect to those of the other, permitting a step-by-step movement of the shaft, thereby effecting movement of the arms from con tact to contact. The relay 31 has a source of alternating current 33 adapted for inclusion in its circuit through the agency of the lower armature switch. of magnet 99, said magnet, when energized, attracting its armature to establish the circuit containing said elements 31 and 33 The line-relay 22 of each subscriber is provided with an armature-switch 100, which, when released,

is grounded. There is but one button 98 y in each group engaged by the switcharin 97 that is grounded by a relay, as 88. The companion buttons 101 are connected each with an armature-switch 1G0, there being many of these buttons 101 as there are i subscribers in the group to which the elements 92--97 are assigned, the buttons 101 in all of the cord circuits (in this case the first sections of the cord circuits, as it is the first group of lilies that is therewith associated) being multipled. As long, therofrn'c, as the arm 97 engages buttons, as 101, that are grounded at 100, which the case when the lines corresponding to said buttons 101 thus grounded are idle, the circuit through the magnet 99 is inaintaincd, said magnet 9!) preferably having another armature (that illustrated above its core) which is grounded so long as the arm 97 is thus grounded, whereby circuit is established through the magnet 38 to withdraw the switches 7 5 to remove the link circuit apparatus and connections, which is desirable until. connection between a link circuit and a calling line is effected. The free end 01' the arm 97, that engaging the buttons 98 and 101, is desirably flared, so that a contact with one button is made before contact with the precodingdmtton is broken. A calling line will have its armatureswitch 100 removed from ground, so that, when the arm 97 strikes the button 101 corresponding to the calling line, cir-, unit through the magnet 99 will be opened," whereby the armature of relay 31' will cease its oscillation and the brushes or arms 92 will be brought to rest upon the terminals 5-6 of the line circuit, which terminals :I' correspond in position to button 101 belonging to the calling subscriber and last engaged by the arm 97 By the same operation the upper armature of magnet 99 is released, so that the magnet 38 is denergizcd and the switches 7 --8 are restored to their normal positions, thereby completing the continuity of the sides of the solectors link circuit. The magnet 48 thereupon becomes energized, circuit being established thercthrough that may be traced from the ground at cut-oil relay 3, whose armatures are thus attracted to complete the connection of the terminals 5--6 with the calling line, the button 5, the arm 92, the switch 8 said relay 48, to the grounded battery 23, whereby another resistance section 71 is out into circuit for the purpose hitherto explained. The calling signal is at this time manifested at 44 the operator in response to this slg l effecting connection of the selected lin circuit with the called line either by the insertion of the connecting plug 17 when the link circuit is of the form shown in Fig. 4 or by the insertion of the answering plug 18 and the connecting plug 17 in the system shown in Fig. 5. In the system shown in Fig. 4 the calling signal el-l is immediately efi'aced when the connecting plug 17 is inserted. In the system ral'lUVll in Fig. 5 this calling signal is immediately cfl'accd upon the insertion of the answering plug 18 that opens the circuit containing the signaling device 44. When the subscribers are through conversation, the operator withdraws the plug or plugs of, the cord circuit, whereupon the contact 102 is connected with the armature 49, which armature is now released because the mag net 4.7 is denergized its circuit is opened at the calling subsoribers sub-station, the (-allingsubscriber having restored his receiver. hen the cord circuit apparatus is restored to its normal idle condition and the armature 43 has thus been released, circuit is established that may be traced from the grounded battery 23, to the armature 49, the contact 102, the relay 103, the armature of magnet 104 (which latter magnet has had a circuit established for it that may be traced from the spring 95 grounded directly or through contact as illustrated, the winding of magnet 104, the armature 106, its magnet 48 still being energized, to the grounded battery 23), the switch-arm 97 to which the same is connected, thence to ground at 100, because the button 101 now engaging said arm 97 is now grounded. The magnet 103 is thus energized to attract its armature into locking engagemcnt with a grounded spring arm 107, whereby a circuit is established for the magnet 99 that may be traced from the grounded bat tery 23, through the magnet 99, the armature of magnet 103, the locking spring 107 in locking engagement with said armature, to ground. The armatures of magnet 99 are thereupon again attracted to break the link circuit at 7 -8 andtoblose circuit through the relay 31 permitting a reoperation of the motor 93 until the tooth upon the switch 95 engages the notch in the ele meat 94. As this engagement is being c0mpleted. a pin 108 strikes an extension 109 of the spring arm 107 to disengage said spring arm from the armature of magnet 103, so that the circuit including magnet 99 will be openedfltsaid spring 'arm, whereby the circuit including the relay 31 will be openedy causing the operation of the motor 93 to cease.

The parts ofFig. 5. that have functions similar to corresponding parts in Fig. 4 are sition.

' that first has connection with a callin given. similar characters of reference, and a detailed description, therefore, of the system shown in Fig. 5 need not be given,

In each of the systems i1lustrated,'thrm is a pilot signal 52; that is, a signal 'bc- 1 longing to a board section or perators 150-- It is apparent that it is not neces sary in all embodiments of my invention to provide a signal 44 for each link circuit, for said link circuits may be so governed in their connection with calling lines that the first unoccupied link circuit is the one line, so that, if an operator were. limite to a single signal 52 for her entire group of cord or link circuits, she would employ said circuits, or rather the idle ones thereof, in their serial order, and she would only cease the employment of said circuits when the pilot signal 52 becomes efl'aced.

It will be seen that the calling signals that are displayed among the operators according to their condition to receive work, are continuously displayed until the circuit of the calling subscriber is manually attended to by the operator. That is, there are switch parts in association with the calling line that are manipulated by the o erator in attending to the wants of the ca 1- ing subscriber, whereby the calling signal is eflaced automatically. Prior to this manual control of the calling subscribers circuit, however, the subscriber may effaee his own si a1. Of course, if this signal is a signal'tfit is common to a plurality of subscribers, such signal is not efi'aceable until all of the lines of said subscribers are connected or the receivers of the calling subscribers have been restored before connection.

The conductors 65-455 constitute circuit fractions that are complemental to the circuit arrangement of the selecting mechanism including the elements 21 and 85.

A' non-numerical switch is one that does not respond to a series of impulses transmitted by a calling device but operates in response to the transmission of an impulse or upon the closure of a circuit. It is obvious that many changes may be made in the embodiments of my invention herein shown without departing from the spirit of the invention, and I do not, therefore, wish to be limited to the precise arrangements and apparatus herein disclosed, but, having thus described my invention, I claim as new and desire to secure by Letters Patent the followingz- 1. A telephone exchange system including telephone lines extending from sub-stations 125 to an exchange, call signal devices operable by the apparatus at the stations of calling subscribers, a pluralit of groups of link circuits for uniting te ephone lines in conversation, each link circuit including m-anu- 180 ally controlled terminals serving to act upon. circuits of said call Signal devices to cli'ect eflacement of the signals occasioned thereby, and selecting mechanism for each group of link circuits for intcrchangeably ussocizih :ing the call signal devices with calling tele phone lines and jointly acted upon by tlu link circuits: of its group.

A. telephone exchange system including telephone lines extending from sub-- stations to an exchange, call signal devices operable by the apparatus at the stations of calling subscribers, a plurality of groups of link circuits for uniting telephone lines in conversation, each link circuit including manually controlled. terminals serving to act upon circuits of said cell signal. devices to effect eflaccment of the signals occasioned thereby, selecting mechanism for interehangeably associating said groups of link circuits with calling telephone lines ttflll. automatic means for connecting a link cir' cuit oil a. group with it calling line.

3. A telephone exchange syetein including telephone lines extending from substations to an exchange, call signal ilericee operable by the apparatus illthe stations oi culling eulwarrilwrs, :3 plurality of groups. of link circuits for uniting telephone llflfT-l in couverisal'imi, each. link circuitincluding; manually controlled tern'iiuals serving to act upon circuits of said call signal devices to effect elfacement of the signals occasioned lhercby, and automatically operated select ing switching mechanism associated with the telephone lines and said link circuits serving to associate the groups of link circults with calling lines and. to effect connection between the answering ends of idle link circuits and calling lines.

al. A telephone exchange sycleni including telephone lines amending; from sub-statimio to on exchange, cell signal devices operable hi the apparatus at the stations of calling Ruhscril'uusl u plura liity of" groups of link circuits for uniting telephone lines in converse-- tion, each link circuit including manually controlled terminals serving to act upon ciu units of said cell signal devices to effect cl;

lurenient of line signals micasioned thereby, and selecting mechanism for each group of link circuits for interchaugeahly associating the call signal devices with lllng); telephone lines and controlled by the link circuits of its group acting together and a calling tele phone line. I

A telephone exchange system including telephone lines extending from substations to an exchange, call signal devices one LLlLllP, by the apparatus at the station-i of calling subscribers, a plurality of group- 1 of link eircuitisfor uniting telephone lines n UOHVEYSA- tion, each link circuit including manually controlled terminals, and selecting niwha n'sm for each group of link circuits for interehangmbly associating the call signal devices; with calling telephone lines and jointly acted upon. by lhe'link circuits of its roup.

(l. A telephone exchange system inc uding telephone lines extending from sub-stations to an exchange, call signal devices operable by the apparatus at the stations of callin sul wribers, a plurality oi" groups of lin circuits for uniting telc 'ihoue lines in conversation, each link circuit inchulin i, more ually controlled terminals, and automatieally operated selecting switching mechanisuiigtssoeiated with the telephone lines and said link. circuits serving to associate the groups of link circuits with calling lines and to effect connection between the cuswcrlug ends; of idle link circuits and calling lines.

7 A telephone exchange system including telephone .lincs extending from sub-stations 85 to on exchange, call signal devices operable by the. apparatus at the stations of calling subscribers, a. plurality of groups of link circuit, for uniting telephone lines in contermtiou, each link circuit nicluding mun hilly vlvflllfullifl terminals, and selecting mechanism for each group 0! link circuits for lililtjli \umgealily associating the call signal devicw with calling telephone lines and controlled by the link circuits of its group acting together and a calling telephone line. A telephone exchange system including telephone lines extending from sub-stations to an exchange, cell signal de ices operable by the ap 'mratus at the stations of eallinj sulmcrihers, link circuits for uniting telephone lines in conversation including inaumlly controlled terminals serving to act upon circuits of said cell signal devices to ell'cct ellucement of the signals occasioned thereby, sa liulr circuits being divided into grimpe, sel "1g lIlBClHU'llE-ll'l at the exchange and opera C by the apparatus at a culling e1ihcrrihrre station serving to select an inrouuilctely oeru ned group of link circuits for assor-iatiim with a calling line, apparatus for each group of link circuits and jointly go verued by the link circuits of its group and iiiterieialed with the aforesaid select ing: mechanism;whereby the association of groups of link circuits with calling lines may be determined, and. automatically operated selecting switching n'iechunism as ociated with the telephone lines and Said link circull-s for ell'ecting connection between the answering ends of idle link circuits of selectcd groups and calling lines. 9. A telephone exchange system including i telephone lines extending from sub-editions. to on exchange; call signal. device-separable by the appuratuslgit'the stations of calling subscribers, link circuits for uniting tele? phone lines in conversation including manholly controlled. terminals serving to act efi'ect efi'acement of the signals occasioned thereby, said link circuits being divided into groups, selecting mechanism at the exchange and operable .by the apparatus at a calling subscribers station serving to select an incompletely occupied grou) of link circuits for association with a calling line, a circuit fraction for each grou of link circuits and complemental to the circuit arrangement of the selecting mechanism serving in one electrical condition to permit the continuation of the operation of the selecting mechanism and in another electrical condition to cause the selecting mechanism to cease its operation, apparatus for each group of link circuits and jointly governed by the link circuits of its grou determining the electrical character of sai circuit fractions, whereby the association of groups of link circuits with calling lines may bcdetermincd, and automatically operated selecting switching mechanism associated with the telephone lines and said link circuits for effecting conmotion between the answering ends of idle link circuits of selected groups and. calling lines,

10. A telephone exchange system including telephone lines extending from sub-stations to an exchange, call signal devices operable by the apparatus at the stations of calling subscribers, link circuits for uniting telephone lines in conversation including manually controlled terminals serving to act upon circuits of said call signal devices to effect eifacement of the signals occasioned thereby, said link circuits being divided into groups, selecting mechanism at the exchange and operable by the apparatus at a calling subscrlbers station serving to select an in completely occupied group of link circuits for association with a calling line, a circuit fraction for each group of link circuits and complemental to the circuit arrangement of the selecting mechanism serving in one electrical condition to permit the continuation of the operation of the selecting mechanism and in another electrical condition to cause the selecting mechanism to cease its operation, apparatus for each group of link cir' cuits and jointly governed by the link circuits of its .group determining the electrical character of said circuit the association of groups of link circuits with calling lines may be determined, and automatically operated selecting switching mechanism for each group of link circuits associated with the telephone lines and said link circuits for effecting connection between the answering ends'of idle link circuits of selected groups and calling lines.

11. A telephone exchange system includ 'ing telephone lines extending from substations to an exchange, call signal devlces operable by the apparatus at the stations of calling subscribers, link circuits for uniting fractions, whereby telephone lines in conversation including manually controlled terminals serving to act upon circuits of said call signal devices to effect cfiacement of the signals occasioned thereby, said link circuits being divided into groups, selecting mechanism at the exchange and operable by the apparatus at a calling subscribers station serving to select an incompletely occupied grou of link circuits for association with a ca ling line, electromagnetic apparatus for each group of link circuits and jointly governed by the link circuits of. its group and inter-related with the aforesaid selecting mechanism, whereby the association of groups of link circuits with calling lines may be determined, and automatically operated selecting switchin r mechanism associated with the telephone lines and said link circuits for elfectin connection between the answering ends 0 idle link circuits of selected groups and calling lines.

12. A telephone exchange system including telephone lines extending from sub-stations to an exchange. call signal devices operable by the apparatus at the stations of calling subscribers, link circuits for uniting telephone lines in conversation including manually controlled terminals serving to act upon circuits of said call signal. devices to efi'ect eifacelnent of the signals occasioned thereby, said link circuits being divided into groups, selecting mechanism at the exchange and operable by the apparatus at a calling subscribers station serving to select an incompletely occupied group of link circuits for association with a calling line, a circuit fraction for each group of link circuits and complemental to the circuit arrangement of the selecting mechanism serving in one electrical condition to permit the continuation of the operation of the selecting, mechanism and in another electrical condition to cause the selecting mechanism to cease its operation, eleetro-magnetic apparatus for each group of link circuits and jointly governed by the link circuits of group determining the electrical character of said circuit fractions, whereby the, association of groups of link circuits with calling lines may be determined, and automatically operated selecting switching mechanism associated With the telephone lines and said link circuits for effecting connection between the answering ends of idle link circuits of selected group and calling lines.

13. A telephone exchange system including telephone lines extending from sub-Sta tions to an exchange, call signal devices operable by the apparatus at the stations of calling subscribers, link circuits for uniting telephone lines in conversation including manually controlled terminals serving act upon circuits of said cell signal devices to eflect efi'aoement of the signals occasioned thereby, said link circuits being divided into 

